CN114278928A

CN114278928A - Air inlet flow guide structure and method for realizing uniform flow distribution from center to periphery of rectangle

Info

Publication number: CN114278928A
Application number: CN202111415815.2A
Authority: CN
Inventors: 周静; 张志刚; 蒋雪峰; 李亭鹤; 牛军; 马同玲
Original assignee: Beijing Power Machinery Institute
Current assignee: Beijing Power Machinery Institute
Priority date: 2021-11-25
Filing date: 2021-11-25
Publication date: 2022-04-05
Anticipated expiration: 2041-11-25
Also published as: CN114278928B

Abstract

The invention relates to an air inlet flow guide structure and method for realizing uniform flow distribution from the center of a rectangle to the periphery, and belongs to the technical field of heat exchanger design. The invention realizes the rectification of the inlet airflow of the heat exchanger through the flow path layout design, so that the inlet airflow is uniformly distributed to four rectangular sides, and meanwhile, the pressure bearing capacity of the heat exchanger under high temperature and high pressure can be improved, further, the heat exchange area is increased, and the heat exchange effect can be better enhanced.

Description

Air inlet flow guide structure and method for realizing uniform flow distribution from center to periphery of rectangle

Technical Field

The invention belongs to the technical field of heat exchanger design, and particularly relates to an air inlet flow guide structure and method for realizing uniform flow distribution from the center of a rectangle to the periphery.

Background

The Li/SF6 combustion heat exchange system as an important component of underwater power plant features high energy density and specific energy, and its product is maintained in solid state under normal pressure, so realizing true closed circulation. However, the reaction of Li/SF6 is very violent, and the temperature of the outer wall surface of the combustion chamber shell can reach over 1000K.

The heat exchanger is used as a part of a Li/SF6 combustion heat exchange system and has the following functions: firstly, working media in the heat exchanger absorb heat from the wall surface of the shell and raise the temperature so as to enter the next part to do work; and secondly, the temperature of the wall surface of the shell is reduced, the combustion chamber is protected to operate safely and stably, and the thermal protection effect is achieved. In order to ensure the flowing heat exchange performance and the structural integrity under high temperature and high pressure, the heat exchanger adopts a fin form, the size of the cross section of a combustion system is 1500mm x 700mm, and the magnitude of the size of the cross section is greatly different from that of the fin, so that the key is to ensure the uniform flow distribution of the heat exchanger after air inlet.

Disclosure of Invention

Technical problem to be solved

The technical problem to be solved by the invention is as follows: the air flow entering from the center of the heat exchanger is rectified to be evenly distributed to four sides of the rectangle, the flow resistance is reduced, and the strength of the heat exchanger is increased.

(II) technical scheme

In order to solve the technical problem, the invention provides an air inlet flow guide method for realizing uniform flow distribution from the center to the periphery of a rectangle.

Preferably, the heat exchange fins are designed as flat fins.

Preferably, the straight fins are dimensioned such that the pitch sf is 2mm and the height hf is 2.5 mm.

The invention also provides an air inlet flow guide structure designed by the method.

Preferably, the structure is an X-shaped flow path structure formed by arranging four parts of heat exchange fins on the bottom surface of the combustion chamber and a flow dividing channel formed by the four parts of heat exchange fins.

The invention also provides a heat exchanger which comprises the air inlet flow guide structure.

The invention also provides a combustion heat exchange system which comprises the heat exchanger.

Preferably, the system is a Li/SF6 combustion heat exchange system.

The invention also provides an underwater power device which comprises the Li/SF6 combustion heat exchange system.

(III) advantageous effects

The invention realizes the rectification of the inlet airflow of the heat exchanger through the flow path layout design, so that the inlet airflow is uniformly distributed to four rectangular sides, and meanwhile, the pressure bearing capacity of the heat exchanger under high temperature and high pressure can be improved, further, the heat exchange area is increased, and the heat exchange effect can be better enhanced.

Drawings

FIG. 1 is a model of a combustion chamber bottom uniform flow distribution structure designed by the present invention;

FIG. 2 is a structural model of a fin designed according to the present invention;

fig. 3 is a flow chart of a flow field obtained by simulation of the present invention.

Detailed Description

In order to make the objects, contents, and advantages of the present invention clearer, the following detailed description of the embodiments of the present invention will be made in conjunction with the accompanying drawings and examples.

The overall layout of the Li/SF6 heat exchange system is based on the structural design of the combustion chamber, the cross-sectional dimension of the combustion chamber is 1500mm x 700mm, and the main heat exchange areas are the bottom surface and the side wall of the combustion chamber.

Cooling working medium (airflow) is fed from the center of the bottom surface of the combustion chamber, heat exchange and flow distribution are carried out on the bottom surface of the combustion chamber, and the cooling working medium uniformly flows to the peripheral side walls of the combustion chamber. Therefore, the air inlet flow guiding method uniformly dispersed from the rectangular center to the periphery is characterized in that an X-shaped flow path design is adopted on the bottom surface of a combustion chamber, a formed uniform flow distribution structure model is shown in fig. 1, straight fins with the pitch sf being 2mm and the height hf being 2.5mm are arranged among flow path branches and used as heat exchange fins, and four parts of heat exchange fins are totally arranged, wherein the left side fins in fig. 1 are shown in fig. 2, airflow enters the center of the bottom surface of the combustion chamber and is distributed to the X-shaped flow path and is distributed to all sides along the channels of the straight fins, the airflow flows in the straight fins in the direction perpendicular to the rectangular sides, the heat exchange area of the bottom is increased while the airflow is uniformly distributed, and the pressure bearing capacity of the air inlet channel is improved.

The four parts of straight fins are arranged as shown in figure 1, a channel without the straight fins is in an X shape, the purpose is to balance pressure loss from the center of the bottom surface of the combustion chamber to each point on four edges of the rectangle, flow loss comprises along-the-way loss and local loss, and through the design of the uniform flow dividing structure, the longer the fluid flow path is, the greater the along-the-way loss is, and the smaller the local loss is; the shorter the fluid flow path, the smaller the on-way loss, the larger the local loss, therefore the cooling working medium gets into the back by combustion chamber bottom surface center, evenly flow in the rectangular plane, and simultaneously, the heat transfer area of cooling working medium and combustion chamber casing has been improved greatly behind arranging straight fin, the heat exchanger heat absorption capacity improves, make combustion chamber casing wall temperature reduce, the selection of straight fin specification need with combustion chamber parameter coupling, prevent that the wall from overtemperature, consider the flow resistance requirement simultaneously, structural strength requirement under the high temperature high pressure etc. straight fin specification design is pitch sf 2mm, height hf 2.5mm, it is very fine, arrange between combustion chamber casing and apron, can also play the effect of strengthening rib simultaneously, the bearing capacity of inlet channel under high temperature high pressure has been improved greatly.

The flow chart of the flow field is obtained by simulating the air inlet diversion model which is uniformly divided from the center of the rectangle to the periphery as shown in fig. 1 and is shown in fig. 3, and it can be seen that the division is relatively uniform. Meanwhile, the total pressure recovery coefficient of the intake flow splitting scheme at a design point is 99.92% by calculation, and the cooling working medium realizes the temperature rise of 200K and the pressure resistance of 4MPa at the bottom of the combustion chamber.

The invention also provides an air inlet flow guide structure which is designed by the method and uniformly dispersed from the center to the periphery of the rectangle, and the air inlet flow guide structure comprises an X-shaped flow path structure formed by arranging four parts of straight fins on the bottom surface of the combustion chamber and a flow distribution channel formed by the four parts of straight fins.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. The air inlet flow guide method is characterized in that four parts of heat exchange fins are arranged on the bottom surface of a combustion chamber, channels without the heat exchange fins are in an X shape to form an X-shaped flow path, so that air flow enters from the center of the bottom surface of the combustion chamber and is divided to the X-shaped flow path, the air flow is divided to each side along the channels of the heat exchange fins, and the air flow flows in the heat exchange fins in a direction perpendicular to the rectangular sides.

2. The method of claim 1, wherein said heat exchange fins are designed as straight fins.

3. The method of claim 2, wherein the flat fins are dimensioned with a pitch sf of 2mm and a height hf of 2.5 mm.

4. An intake air guide structure designed by the method of claim 1, 2 or 3.

5. The structure as claimed in claim 4, wherein the structure is an X-shaped flow path structure formed by arranging four parts of heat exchange fins on the bottom surface of the combustion chamber and a flow dividing channel formed by the four parts of heat exchange fins.

6. A heat exchanger comprising the intake air guide structure as claimed in claim 4 or 5.

7. A combustion heat exchange system comprising the heat exchanger of claim 6.

8. The system of claim 7, wherein the system is a Li/SF6 combustion heat exchange system.

9. A subsea power plant, characterized in that it comprises a system according to claim 8.